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We had a bridge collapse this morning! Here is the Courant article about it. (Picture from the Courant) When I got to work this morning, I checked out the news, and the story was just breaking. The Courant initially said it was the Maple Ave bridge. I checked out the TRU to be sure, and breathed a sigh of relief when I found it wasn't on a state road. The photos didn't match up, though, and I quickly figured out it was the four-lane Route 63 bridge in Naugatuck. The Courant corrected their story around 8:20. This bridge has been under construction for several years. The traffic engineer who worked on it originally is gone now. I feel bad for my coworker Claudel who's going to have to handle all the detour routes and staging now. He never got to see the project in the first place, but he'll have to fix things in a hurry now. So, what about the bridge? As we usually do with bridges that have to stay open, we cut it down to one lane in each direction, demolished half of the bridge, and built half of the new one alongside. Last week, June 7, we finished the new half and shifted traffic onto it to demolish the remaining old half. This is the half that collapsed. Some sources say a crane hit it; I think, personally, it wasn't demolished properly. We'll see what really happened in the days to come. An excavator operator sustained serious injuries, but nobody else was hurt. The bridge is now closed to traffic, as is the Metro-North rail line running below it, indefinitely. Edit: Courant was wrong, he wasn't a crane operator after all. You figure the country's oldest newspaper would check its facts once in a while. Cichlidae fucked around with this message at 21:47 on Jun 15, 2010 |
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Jun 15, 2010 17:17
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Interesting. I saw the bridge was closed and the traffic in Naugatuck was insane but assumed it was just because they were working on it. They were really hacking away at the part that collapsed yesterday. (The bank in Naugatuck was robbed today too. When it rains, it pours!)
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Jun 15, 2010 19:25
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Cichlidae posted:The one I have the most experience with, on I-93 south of Boston, is done manually. They stick come cones out, block the lane, and then send the zipper truck down to shift over the barrier. Traffic control on freeways is pretty tough to do automatically, because a good part of it involves getting the motorist's attention. Having a gate across the road won't have the same impact as a state trooper in his cruiser. Ahh ok. I was always wondering about that, I hear the expressways are open out of the city till noon then open into the city for the rest of the day. I've had the unfortunate pleasure of Chicago morning rush hour and people always try to pile in the expressway, I imagine it's pretty hard to do something like automatically if everyone tries to squeeze through. Thanks  .
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Jun 16, 2010 04:43
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I lived in California for a time, and always wondered about the traffic signals there, as opposed to the ones here in Connecticut and elsewhere here in the east. Why do we here in Connecticut usually have two signal heads suspended above the intersection, while in California, they usually have one, with a pole mounted signal at the corner? Plus all the signals are mounted directly on poles, as opposed to usually strung on cable between poles. For a typical example, this is the intersection of Sunrise Blvd and Greenback Lane in Citrus Heights CA:  Here IS an intersection with two overhead signals and the pole mounted one at the corner. Not sure why, both intersections have the same amount of lanes leading to them. (Intersection of Galleria Blvd and Roseville Parkway in Roseville, CA):  Here's a similar intersection in Connecticut for comparison (Tolland Tpke and Buckland St in Manchester, CT)  Is this a preference thing, or is there a practical reason? By the way, it sucks that the Google street view quality for Connecticut is so crappy.
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Jun 16, 2010 11:40
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porkfriedrice posted:I lived in California for a time, and always wondered about the traffic signals there, as opposed to the ones here in Connecticut and elsewhere here in the east. Why do we here in Connecticut usually have two signal heads suspended above the intersection, while in California, they usually have one, with a pole mounted signal at the corner? Plus all the signals are mounted directly on poles, as opposed to usually strung on cable between poles. The MUTCD requires at least two signal heads for the major movement, and that both signal heads be visible for a minimum distance in advance. A pole-mounted signal head on the right could easily be blocked by a vehicle that pulls too far forward on the side street, a truck parked on-street, or a truck in the right lane on the main street. Connecticut standards say the heads can't be more than 20 feet apart, so that limits their placement as well. Finally, we like to put our signal heads above the lanes they control, so that approaching cars at night can use them as a beacon to judge where they're supposed to go. Having a post-mounted head on the side of the road could lead someone to drive off the road (and remember, we have to design for geriatrics and drunks, so this isn't as strange as it seems.) We use mast arms as well, just not everywhere, as we build them to much beefier standards than California that limit their length to 40 feet and make them quite expensive. West Hartford, for example, mostly uses mast arms (because they have money). As to why California has two configurations in the two pictures, speed is also a factor. When the 85th percentile speed is 45 or above, there have to be 3 signal heads for the major movement.
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Jun 16, 2010 12:40
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noblergt posted:http://www.publicpurpose.com/hwy-tti99ratio.htm Dallas is basically a big intersection. Add Ft. Worth to the mix and the DFW area becomes some sort of mystical hyper-nexus of roadways. Who needs responsible urban planning and development?? We got LAND, LAND, LAND!!
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Jun 16, 2010 15:33
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Stew Man Chew posted:Dallas is basically a big intersection. Add Ft. Worth to the mix and the DFW area becomes some sort of mystical hyper-nexus of roadways. Who needs responsible urban planning and development?? We got LAND, LAND, LAND!! Not to mention a ridiculous amount of parking lots, and the fact that its freeway network looks like a giant dong. Here are some more photos from the bridge collapse:    I'm pretty sure that last pic explains why the worker was injured.
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Jun 16, 2010 21:56
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What are the doors in these bridge abutments? This is the West Road overpass on Route 11 in Colchester, CT. There are four doors, one on each side of both the northbound and southbound sides. Always wondered what was behind those doors.
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Jun 19, 2010 03:18
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porkfriedrice posted:What are the doors in these bridge abutments? This is the West Road overpass on Route 11 in Colchester, CT. There are four doors, one on each side of both the northbound and southbound sides. Always wondered what was behind those doors. They're probably for inspecting the wingwalls and abutments. I'll try to stop down there next time I go in the field and check it out in person. I can also ask around the office when I get back from vacation, but nobody here was around when that bridge was built in the early 1970s. Maybe one of the bridge design guys will know. I went out in the field (Hartford) again today for the Busway, and took some pictures, but nothing particularly interesting. It was a little surreal, though, seeing sandpipers strutting around on the abandoned rail spurs. What are sandpipers doing 40 miles from the coast?
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Jun 19, 2010 04:41
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Cichlidae posted:They're probably for inspecting the wingwalls and abutments. I'll try to stop down there next time I go in the field and check it out in person. I can also ask around the office when I get back from vacation, but nobody here was around when that bridge was built in the early 1970s. Maybe one of the bridge design guys will know. Is that common? As far as I've seen, this is the only overpass that has had these doors, but what do I know.
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Jun 19, 2010 05:17
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porkfriedrice posted:Is that common? As far as I've seen, this is the only overpass that has had these doors, but what do I know. It's the first one I've seen. There are other reasons to build doors into abutments: safe rooms, maintenance storage, electronics, getting rid of surplus doors... I'm sure someone will know.
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Jun 19, 2010 05:42
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Cichlidae posted:It's the first one I've seen. There are other reasons to build doors into abutments: safe rooms, maintenance storage, electronics, getting rid of surplus doors... I'm sure someone will know. Secret CIA base? I will assume that's the case if you suddenly stop posting. Are there any rules about where U-turns should be allowed? I know the law on this varies from state to state, but I was wondering if there might be some general design rules or something. In California, you can make a U-turn at any left turn lane unless it is specifically forbidden by a sign. Thing is, it appears to be completely random as to where they decide to forbid it versus where it's allowed. You can get two intersections in a row, both absolutely identical, and one will have a "No U-Turn" sign on it while the other doesn't. Sometimes busy intersections don't allow U-turns, while seemingly identical busy intersections elsewhere in town do. Same with more rarely-travelled streets. It's almost as if they build an intersection and at the end, some dude flips a coin and sticks up a "No U-Turn" sign up if it comes up tails. I understand forbidding in places where the cross-street traffic gets a green right arrow during your green left arrow phase, or places where there isn't enough room for the average car to make a U-turn. Other than that, what's the logic here? I ask you because someone was probably getting stabbed or raped somewhere while a cop was staking out this area waiting for evil U-turners (identical signals at both intersections btw)... 
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Jun 19, 2010 10:27
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Well on that example it seems that the righthand one has more lanes and a physical median, while the lefthand one does not.
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Jun 19, 2010 10:49
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noblergt posted:Well on that example it seems that the righthand one has more lanes and a physical median, while the lefthand one does not. Same number of lanes (2 on each side + turn lane), and the difference in the median is just a foot or two (not to mention if you go another block farther there's yet another intersection that allows U-turns which is identical except it has no physical median at all). It's very puzzling.
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Jun 19, 2010 10:59
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my only guess would be that the one on the left is too close to another intersection (that little side road there)
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Jun 19, 2010 14:03
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porkfriedrice posted:Always wondered what was behind those doors. Cichlidae posted:It's the first one I've seen. There are other reasons to build doors into abutments: safe rooms, maintenance storage, electronics, getting rid of surplus doors... I'm sure someone will know. grover fucked around with this message at 14:36 on Jun 19, 2010 |
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Jun 19, 2010 14:33
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Choadmaster posted:Secret CIA base? I will assume that's the case if you suddenly stop posting. There are three major reasons we forbid U-turns here: 1) If the pavement isn't wide enough for the design vehicle (usually a WB-50) to make the turn, we can forbid them. Funny thing is, in many states, vehicles are required to U-turn into the nearest lane, hugging that 4-foot median nose. Hardly anyone does, and, like I said, it's assumed that trucks will pull into the shoulder. We often design bulb-outs (extra pavement on the shoulder) specifically to allow U-turns. 2) If the adjacent right turn has an overlap green arrow. Just like you mentioned. There is a sign we could use that says "U-turns yield to right turn," but that's pretty complicated for some drivers to understand, and it's much easier to ban the U-turn. 3) If left turns are forbidden for whatever reason, U-turns are also forbidden. Simple enough. Usually, we'll only forbid U-turns if there's a physical median. Need somewhere to put the sign, right? I should also note that U-turns are one of the last things on a traffic engineer's mind when he's designing a big signal like that. Sometimes we forget things grover posted:Hobos. I'll have to bring my hobo repellent. All the other overpasses around there were built at the same time, and the ones I've worked on are just fill behind cast-in-place abutments with integral wingwalls. Either way, I bet there's an interesting story behind this overpass.
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Jun 19, 2010 18:08
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Was on the recently-redone section of I-35 south of OKC today and saw these new overhead signs. Click here for the full 800x478 image.  Click here for the full 800x478 image. Any idea why they switched to that design? First time I've ever seen those. All the other ones use seemingly-identical supports and posts. Cheaper, maybe?
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Jun 19, 2010 23:55
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Citizen Z posted:Was on the recently-redone section of I-35 south of OKC today and saw these new overhead signs. Sign support design is done on a state-by-state basis. Here's what we've had in Connecticut:  Back in the old days, we used monotube sign supports. They're quite structurally unsound, so by the mid 1980s, almost all had been replaced by trusses. The truss sign supports are quite nice, but tend to rust out and collapse. So, in the early 1990s, we switched over to cruciform arch... Which worked just fine, until AASHTO came out with a study around 2001 that said that kind of sign support is vulnerable to galloping. That's when trucks pass beneath at a certain frequency, and the sign support rocks from side to side, eventually causing fatigue failures. We switched over to the awesome-looking tubular arch shown in your picture. Until this year. Because now, the state government has decided that, instead of going with a design that's worked well for nearly 10 years, we should let the contractor design-build all of our sign supports. What's the model they're going by? The old, cheap monotube. We don't even know ahead of time what it'll look like; we just give the contractor a blank check and hope the support lasts 20 years. Enjoy your tubular arches while you can!
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Jun 20, 2010 02:18
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Cichlidae posted:Until this year. Because now, the state government has decided that, instead of going with a design that's worked well for nearly 10 years, we should let the contractor design-build all of our sign supports. What's the model they're going by? The old, cheap monotube. We don't even know ahead of time what it'll look like; we just give the contractor a blank check and hope the support lasts 20 years. Is this why the I-84 WB Exit 63 sign hasn't been replaced yet? (the one where the dump truck entered the highway with the back still up and got caught up in the sign rendering his truck perpendicular to the highway)
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Jun 20, 2010 20:41
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Lobstaman posted:Is this why the I-84 WB Exit 63 sign hasn't been replaced yet? (the one where the dump truck entered the highway with the back still up and got caught up in the sign rendering his truck perpendicular to the highway) The sign support itself survived the impact, but the inspectors found a small crack in its foundation. We've been debating for the last several months whether to inject some grout into the crack, or replace the foundation altogether. The whole thing makes my boss pretty furious, because we just want a sign out there. They could easily put up a side-mounted sign like we did on Route 9 or Route 4 when those foundations broke, but not until the structural folks figure out how long it'll be until the overhead support is fixed. Edit: The cost of fixing/replacing the foundation is also an issue. The guy who hit it with the truck is liable, but we still need to pay for the repairs first and bill his company afterward. Money's extremely tight, and even if they could agree on what they're doing, I don't think we'd be able to repair it right away.
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Jun 20, 2010 21:16
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Cichlidae posted:Usually, we'll only forbid U-turns if there's a physical median. Need somewhere to put the sign, right? I've seen them hang No U-Turn signs from light wire supports and mast arms here in Massachusetts. When there's a will, there's a way...
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Jun 21, 2010 15:44
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A question / comment about ramp meters - is there anything that defines where the in-pavement triggers should be for ramp meters? Most of the onramps in the Phoenix area now have meters on them, but they're set up so that in the absence of any cars, they lock down on red. The strange thing is, the triggers in each lane aren't set at the same point. The right lane has a trigger located a decent bit up the ramp from the meters. When you approach a set of meters on a dead red, if you're planning on obeying them, you're already well on the brakes at this point - but you're still a ways back. As soon as you cross the trigger, the light flashes green...but because it's green for such a short time, even if you expect it and you stomp on the gas as soon as you see it green, it'll go back to red before you get to it. On the left lane, the trigger is maybe a car length before the meter. Hit it, light goes green, and even though you're nearly stopped, you're right there so you can get on it and go without a full stop.
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Jun 21, 2010 18:15
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Wisconsin just passed legislation to allow u-turns at all unmarked intersections which left cities all over the state scrambling to post no u-turn signs.
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Jun 21, 2010 18:44
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kefkafloyd posted:I've seen them hang No U-Turn signs from light wire supports and mast arms here in Massachusetts. When there's a will, there's a way... It's easy to argue with overhead signs in Connecticut. Our sign brackets only hold 24" wide signs, though the MUTCD mandates larger signs for the most part. Don't tell anyone, though  IOwnCalculus posted:A question / comment about ramp meters - is there anything that defines where the in-pavement triggers should be for ramp meters? This section of the MUTCD specifies how ramp metering is to be treated, but it doesn't mention actuation. Loop detectors, after all, are not traffic control devices! The AASHTO guide linked therein may have specifications, but like all AASHTO publications, it's not free. I don't know why Phoenix's loops are set up like that, anyway, because it would be possible to dodge between them and not make a call. Neutrino posted:Wisconsin just passed legislation to allow u-turns at all unmarked intersections which left cities all over the state scrambling to post no u-turn signs. Good to see uniformity is spreading! Maybe someday we'll get a nationwide treatise on yellow times.
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Jun 21, 2010 23:38
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Cichlidae posted:This section of the MUTCD specifies how ramp metering is to be treated, but it doesn't mention actuation. Loop detectors, after all, are not traffic control devices! The AASHTO guide linked therein may have specifications, but like all AASHTO publications, it's not free. I don't know why Phoenix's loops are set up like that, anyway, because it would be possible to dodge between them and not make a call. Huh, yeah, you're right - they're definitely far enough apart that you could go in the left lane, not trigger the right one, and then change lanes. It just popped in my head this morning on my way in - there was a truck a good bit ahead of me in the right lane, so I went left. He was slowing down when he got to the point where the right lane triggers, got a flash of green, and then red again - so he stopped. He'd been stopped a second or two before I caught up to him, but the way those triggers work, as soon as I did, I got the green and blew right on past him. It gets really old when everyone decides to line up in the right lane for some reason and the left clears out - the meter ends up working at about 1/4 of its intended volume.
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Jun 22, 2010 00:11
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http://www.courant.com/news/opinion/editorials/hc-editorial-highway-workshop-20100622,0,5072746.storyquote:The highway construction and urban-renewal programs of the mid-20th century tore swaths through large cities such as Buffalo and mid-sized municipalities such as Hartford, but also wreaked havoc on many small cities. New London is a textbook example. Have you heard anything about this? What could they do with the 95/32 interchange? It really seems there is no money for this.
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Jun 22, 2010 09:59
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porkfriedrice posted:http://www.courant.com/news/opinion/editorials/hc-editorial-highway-workshop-20100622,0,5072746.story That seems to just be a city initiative. Even with regional support, which isn't likely, New London would have basically no chance of getting the DOT and FHWA on board. The Gold Star bridge was doubled for a reason, after all. Reducing it back to one span would cut it to two lanes in each direction, which is insufficient for the current volume and the number of exits and entrances on each side. We have plans to increase all of I-95 from Branford to the Rhode Island line to three lanes in each direction, so cutting it to two in the highest-volume area would really piss off the FHWA. The interchange on the Groton side of the river is ancient, and hasn't changed appreciably since 349 was built. I have a feeling that New London doesn't care about that, though. They're all upset about the 95/32 interchange. The collector/distributor roads will eventually go all the way to the 95/395/11 interchange if that ever gets built. Waterford, I'm sure, is very eager for additional expansion in the area, which is why I don't think there will be regional support. For the Route 32 interchange itself, sure, it's complex, but it's an efficient use of space given the volume of people who are expected to use 32 to get to 395. They might be able to shrink it to a SPUI or diamond if the 95/395 interchange were re-done to allow full access, but that's not happening anytime soon.
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Jun 22, 2010 16:36
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I wonder what you think about this intersection: http://maps.google.com/maps?q=gilro...Q&cbp=12,0,,0,5 There are two left turn lanes on either side which have raised white bump markers to guide traffic through. Most of them are missing and I've been almost hit I don't even know how many times by people making erratic left turns. What's the proper way to handle multiple left turn lanes in a single intersection?
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Jun 23, 2010 20:45
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Ron Jeremy posted:I wonder what you think about this intersection: We don't use raised pavement markers here, since they get scraped off by plows. Instead, we use cat tracks, which are 2-foot lines with 6-foot gaps between. In general, we use them anytime there are multiple turn lanes or the intersection is slightly offset and it's hard to tell which lane you're supposed to go into. A bigger concern with double- (and triple-) lefts is providing enough pavement width. Normal lanes are 12' wide, but in a double-left, we provide 18 feet or more. As to drivers changing lanes while turning, there's very little that a traffic engineer can do to combat it. People turning in a double-left will tend to stagger their cars so that, if the person next to them suddenly changes lanes, they won't get hit. It also makes merging downstream much easier, as it's very common here to have a double-left merge down into a single lane shortly past the intersection.
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Jun 23, 2010 22:02
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http://www.courant.com/news/opinion/hc-op-medians-mowing-0626-20100626,0,2758175.storyquote:Mowing Highway Medians Wastes Money I know that landscaping isn't your field, but I wanted to know your thoughts. Does the author have a point when it comes to the tall grass being a safety benefit? Is appearence the only reason that the DOT mows? Maybe if the grass was so high that you couldn't see the other side of the road, it would cut down on rubber-necking. (half joking)
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Jun 26, 2010 03:46
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Short grass sure makes it easier to see if there's wildlife in the median, for one.
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Jun 26, 2010 04:07
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If you live anywhere where poo poo catches fire, that poo poo can and will catch fire. Especially when it dies and dries out during the dry season.
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Jun 26, 2010 04:35
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Another "why the hell do they do this?" post: Dorr and North Byrne in Toledo, OH  Link Dorr is the east/west road, Byrne obviously comes in from the south. The problem is that there's a fairly long protected left for those coming in from the east on Dorr. Unfortunately, there's a "No Turn On Red" sign for those waiting in the right turn lane on Byrne. Now there's a dedicated light for the right turn lane, but for some reason I can not understand it is red through not only the Dorr left but also a portion of the Byrne left. I turn right at this intersection almost every time I'm in Toledo and it pisses me off to be waiting there for 30-90 seconds while there's as far as I can see absolutely no reason I shouldn't be able to at least right on red. The University of Toledo campus is about 1000 feet east as well, so police presence is always heavy as well.
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Jun 26, 2010 04:50
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kefkafloyd posted:Short grass sure makes it easier to see if there's wildlife in the median, for one. Good point. I've seen a lot of dead deer on the side of the road lately. We probably don't need a lush grazing area in the middle of a busy road. Choadmaster posted:If you live anywhere where poo poo catches fire, that poo poo can and will catch fire. Especially when it dies and dries out during the dry season. Also a good point. Though this isn't as much as a problem here in Connecticut. I remember driving on I-80 in California and seeing random patches of grass on fire, they definitely don't need tall grass there. I'm not saying that it never happens here, just not as prevalent as other areas.
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Jun 26, 2010 04:58
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I've noticed a number of four-way intersections will have red on all approaches for a solid 15-30 seconds without offering a pedestrian phase in this timeframe. Why would this be a good idea?
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Jun 26, 2010 04:59
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porkfriedrice posted:http://www.courant.com/news/opinion/hc-op-medians-mowing-0626-20100626,0,2758175.story Well, right off the bat, this guys is wrong about the purpose of medians: There are two purposes for median strips. The most important is to keep traffic in one lane from running head-on into traffic from the other direction. A second reason is to keep the lights of on-coming traffic from blinding drivers in the other lane. Preventing head-on collisions is one purpose, yes, but blocking headlights isn't why we have medians. More important functions are providing recovery areas for cars that run off the road, offering drainage for wide swaths of pavement, and reserving land for future freeway expansion. Have you ever tried driving through tall grass in a normal car? It's like driving through a big puddle. There's an incredible amount of drag. While that could be spun as a benefit, slowing down errant cars, it also makes it harder to maneuver or accelerate to freeway speeds if you've pulled into the median. As Choadmaster and Kefkafloyd noted, fires and wildlife are also a concern. One more dangerous issue is fixed objects. The article suggested planting bushes in the medians. Anything with a trunk wider than 4" becomes a fixed object, and a deadly hazard to any car that strays off the road. The trees currently beside the road are outside the clear zone, which is generally 30' from the edge of the travelway on freeways. When medians are narrower than 60', there's no clear zone, and no safe place to put trees or bushes. High grass can also hide other fixed objects, like rocks and trees, which pose a hazard to motorists.
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Jun 26, 2010 16:08
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wolrah posted:Another "why the hell do they do this?" post: If the sight distance is substandard, that could be the cause, but it looks fine from that satellite photo. The lane geometry doesn't preclude RTOR by itself. It could just be a local rule (some towns are notorious for this) to post NTOR within x distance of a school, or if the pedestrian volume crossing is at least y. Out of curiosity, why wouldn't you cut through the adjacent residential area on the right? The western entrance isn't signalized, and Secor Road north of its intersection with Dorr looks like it carries some heavy volumes, so the Secor Road phase should come in often. Crackpipe posted:I've noticed a number of four-way intersections will have red on all approaches for a solid 15-30 seconds without offering a pedestrian phase in this timeframe. I've never seen one like this, except for a proposed Busway intersection I'm planning with a 16-second red clearance. Can you give me an example of one, so I could get a look at its signal plan?
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Jun 26, 2010 16:15
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Cichlidae posted:If the sight distance is substandard, that could be the cause, but it looks fine from that satellite photo. The lane geometry doesn't preclude RTOR by itself. It could just be a local rule (some towns are notorious for this) to post NTOR within x distance of a school, or if the pedestrian volume crossing is at least y.
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Jun 26, 2010 16:36
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Large Hardon Collider posted:I think he means that giving right-turning traffic a green wouldn't lead to any conflict. There's an intersection like that turning onto mass ave in cambridge; the one way street has a protected right turn and then a protected left turn, during which right turns are prohibited. Hugely annoying, especially since the right turn comes first, since if I miss it I have to choose between making a pointlessly illegal turn or waiting 2-3 minutes. Ah yes. If they do have a signal head up, there should be an overlap, definitely. In that case, it's possible that either the signal isn't configured properly, or someone decided that overlaps were verboten. In our office, the Projects section is strongly against overlaps, and the Studies section likes them. Sometimes Projects will put up a signal with no overlaps, and then Studies will revise it and put them in. If it were the other way around, you could end up with a design like that: meant to have an overlap, but revised to remove it.
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Jun 26, 2010 16:56
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